A German palliative care doctor has been sentenced to life imprisonment for killing 15 of his patients.

A court in Berlin on Wednesday found the 41-year-old man, named only as Johannes M. in line with German privacy rules, guilty of murdering 12 women and three men between September 2021 and July 2024.

The authorities believe these killings could be just the tip of the iceberg. Prosecutors are currently investigating dozens of other incidents involving the doctor.

His victims were between the ages of 25 and 94. The court heard how they were all critically ill, but that their deaths were not imminent.

Prosecutors said that during home visits, the doctor administered a lethal combination of various medicines without his patients' consent.

On several occasions, they said he set fires to cover his tracks.

In July 2024, shortly before his arrest, prosecutors said the doctor killed two patients in a single day - a 75-year-old man at his home in central Berlin and, a few hours later, a 76-year-old woman in a neighbouring district.

They said the doctor tried to set fire to the woman's house, but failed.

For much of the trial, which has gone on for about a year, the doctor said nothing. But last month, he confessed to having "killed people", twelve of his severely ill patients.

He told the court he had convinced himself that he was doing the right thing, sparing them "suffering and infirmity".

"Throughout it all, I thought this was the best thing for everyone," he said.

He said he apologised for all the suffering he had caused.

The authorities suspect him of having killed further patients. Prosecutors are currently investigating 76 other cases.

German media say if the further cases are proven, and he is found guilty, it would be one of the worst cases of serial murder in Germany's history.

The doctor told the court that he would "get involved much earlier in the forthcoming proceedings".

Earlier in the trial, relatives of the victims told the court they still couldn't believe it.

The mother of the youngest victim, a 25-year-old woman who died in 2021, was in tears. "She never said she didn't want to live anymore," she said.

The son of a 72-year-old woman who died in 2024, said his mother had had plans to go to the Baltic Sea with her sister. "My mother wanted to keep on living," he said.

The court ordered that the doctor be put in preventive detention, following his prison sentence. It also imposed a lifetime ban on him practising medicine.